This invention relates to tinting systems for color additives used in paint, plaster, and similar surface coatings, and is more particularly directed to a system for accurately and reproducibly tinting such products.
In the building trades many surface coating materials are used to finish the exterior walls and interior rooms. These materials, which include paint, plaster, stucco, and other architectural surface products, are generally colored by the provision of a neutral-color base coating material and a selection of tinting additives. Judicious and artistic combinations of the tinting material mixed into the base material may create a wide range of colors suitable for most architectural and engineering demands.
The base materials for each type of surface coating are generally distributed in canisters, pails, or barrels, and the tinting material is mixed into each container individually. The mixing step may take place just prior to use of the material, or may be accomplished by the distributor prior to sale. In either case, it is critical that the tint proportions and amount are identically matched for all the containers, so that there will be no color variations in applications that require multiple containers of the material. Tints are generally dispensed from finely graduated measuring cylinders into a mixing cup or similar container. The tint materials are fully mixed in the cup, and then poured into the pail or can of base surfacing material. For mixes that are to be stored for any length of time or shipped, it is a common practice to add water to the tint mix in an amount sufficient to maintain a complete intermixture of colorants, while not causing precipitation or settling. The thinning effect of the added water renders the mixture unsuitable for packing in threaded vials or containers, due to the potential of leakage past the threads.
Although this system is capable of creating batches of tint mixes that have virtually identical proportions, there is a difficulty in delivering 100% of the tint mix from the cup. It is necessary to scrape the residue of tint from the cup to assure that the entire tinting lot is mixed into the base material. Considering the staining potential of the tinting mix, it often happens that the individual mixing the material may avoid a messy task by avoiding scraping all of the tint from the mixing cup. The result is a slight variation in the amount of tinting mix added to each container, causing color and color density variations in successive lots of tinted surfacing material. These variations may be too subtle to be noticed prior to application when it is liquid or wet, but may become apparent after they have dried and set. Repair or reapplication may be required, causing increased cost as well as dissatisfaction with the product.